There's a chap up the road from me has a few tanks, although I don't think he has anything smaller than a 'Chieftain', He hires them out for films & such, and also does 'off road' driving courses for the more 'well-off' amongst us!!
Mind you, even with global warming freak weather, I think they might be a bit awkward as anchors!

If I am on a hard surface ...concrete , or slabs or cobbles ...and getting a fixing into the ground is not possible to tie down to , then this is what I do ( if there are also no fixed objects like posts or benches to fix to)

I carry four weight bags in the passeger footwell of the van . It isnt often I have a passenger , so they tend to just stay there.

They are made of red and white striped market awning plastic ( I got a big bit to make a pretty groundsheet for kids to sit on , and this was some of the leftovers.

Wide webbing straps are sewn around the outside to form strong carry handles . Each bag also has a big metal D -Ring to tie off to.
The bags have wide velcro along the opening , and inside is a sealed inner bag of gravel , which can be removed.

I did this , so if I ever knew I needed weight bags abroad , I could remove the actual 'wieght' part and just fly the empty bags in my luggage.

But this led me to thinking about this topic ( Yes I am getting back to beaches now LOL)

On a sandy beach what you have is an abundance of sand.

So why not carry four large empty weight bags , and use that nifty portable shovel to fill them with as much sand as you need to guy rope down to?

You only have to put in as much sand as the wind dictates ...if the wind picks up during the day ..just shovel in more kilos of freely available balast.

At the end of the day , tip it all out ..less to carry back to your vehicle.

But if you find youself suddenly facing heavier gusts ..then the options so far suggested , have ranged from very big tent pegs , to lengths of steel and metal stakes , to railway angle irons at 18 kilos each

Doubtless all these work , and are more tired and tested than my guesses ... but I know what I would rather carry in my pack : and its a set of four large , but empty weight bags ....fill em up and tie off to them once the windstrength gets to more than the regular bang-in pegs can cope with.

With respect Richard, I doubt very much whether a heavy bag, a very, very heavy bag, would be anywhere near as effective in wind as tent pegs. The weight of the bag is not of great consequence. Even a very heavy flat object would slide on wet sand. If you tied your tent to a bag of sand the only thing that is holding the position is the friction between the bag's surface and the sand's surface. If you could slide the bag into position yourself, then the wind against the booth could also cause it to slide. Not lift it you understand, but slide it.
A tent peg correctly placed cannot pull out. In very windy conditions the danger is that the booth uprights twist and break because the pegs refuse to give. That isn't theory - that has happened to me. That is where Peter's idea of the addition of a couple of stakes tied to the legs sounds such a good idea.
Working, as I do, on the North Wales coast, I have a constant battle with wind, and my booth has the scars to prove it. I am never worried when I can use guy ropes and tent pegs - the problems arise on surfaces where pegs can't be used and I have to depend on weight in some form for stability. This is where your bags along with John's lumps of cast iron, my railway sleepers , James' Arnott's stage weights and Tony James pneumatic drill all come into their own.

I don't know where you find this sand so dry you can't get a peg or stake to hold in it Tony. All the beaches I've known have been adjacent to quite a large amount of water, and were at least partially submerged daily.
You may be talking about indoor mock beaches, but in this case I wouldn't have thought wind would be much of a problem - certainly not sufficient to be burying sand bags with a army entrenching tool?